Modern mattresses generally include an inner construction, covered by a mattress sack. A mattress sack is formed from a top and bottom panel and a side panel, joining the top and bottom panel.
Finished mattresses are generally heavy and bulky. This weight and bulk has a direct impact on manufacturing cost, because the weight and bulk are more likely to cause injury, for example. In addition, existing and future government regulations ("OSHA" regulations, for example) have provisions concerning the number of people necessary to flip mattresses.
While mattress manufacturers desire lower cost manufacturing processes, they also demand a product with high quality sizing. For example, it is generally understood that it is relatively simple to attach a top panel of a first peripheral length and side panel having a same length edge. However, such a construction produces an unacceptable product. This is so, because the final construction is susceptible to unsightly "radial bunching" of the side panel when the mattress is loaded, for example if a person sits on the mattress (radial bunching refers to the effect produced when the side panel bunches outwardly and radially). To avoid bunching, mattress manufacturers attach the top and bottom panels of a first peripheral length with a side panel having a shorter edge length. This, however, has been performed manually with skilled labor, which increases the manufacturing costs. In such operations, a skilled operator pulls on the side panel, while pushing and manipulating the top panel to fit the two together. This is usually done with known tape-edge closing machines having a sewing machine and track mechanism. The operator follows the machine around the periphery of the mattress first manually fitting the side panel and top panel in conjunction with the machine. Then, the mattress is flipped, and the operator follows the machine around the periphery of the mattress manually fitting the side panel and bottom panel. As a result, the skilled fitter is needed to fit both edges, i.e., the top and side, and the bottom and side.
Accordingly, it is an object of the invention to provide a method and apparatus for forming partial sacks having a top panel with a peripheral edge length and a side panel with a shorter edge length so that manual fitting need be done for one edge only.